Better yield is a perennial, sometimes elusive goal for farmers and plant breeders.

Modern plant breeding and farming practices improved yields in the past century, yet little is known about which genes influence yield or how they do it.

A University of Nebraska agronomy team is tracking down some answers. It's zeroed in on what it believes is a major gene responsible for wheat yield. Wheat Breeder Steve Baenziger and Molecular Geneticist Kulvinder Gill head the Institute of Agriculture and Natural Resources team that includes Biometrician Ken Eskridge and Statistician Dan Nettleton. They've already narrowed the gene's location to a small segment on the tip of one of wheat's 21 chromosomes.

Their research suggests they're after a single gene that can boost yields by 14 percent to 16 percent. That's especially exciting since yield is extremely complex and scientists long have thought that finding one gene with a major yield influence was unlikely.

"No one has material like this where you can actually find a major yield gene on a small segment," Gill said. "This is very innovative, new information. My hunch is that a single gene is responsible."

A veteran plant breeder and geneticist, Baenziger knows just how much there is to learn about genes' workings.

"We have a chance to get at the genetic mechanisms that underpin this trait. That's what functional genomics is all about," he said. Functional genomics essentially is the study of how genes function and their roles in important traits such as yield.

Today's gene search builds on Baenziger's earlier research. In the early 1990s, his team identified the chromosome at the heart of current research. Extensive field studies using unique wheat lines developed at NU in the 1950s showed this chromosome boosted yields 15 percent.

Since then, IANR scientists and graduate students have scrutinized this chromosome. They first identified the part of the chromosome region associated with yield. More recently, they narrowed it to only 29 percent of the chromosome, identified numerous molecular markers associated with yield and are looking for more markers to help pinpoint the yield gene's precise location.

Their approach is targeted.

Several years ago Gill's team found that 80 percent to 90 percent of the wheat genome contains no genes so they concentrate their molecular mapping efforts on only the important gene-producing regions.

"We are going at this very systematically to be a lot more efficient," he said. "We're targeting a small region that contains 60 useful genes."

Gill and Baenziger expect to find and clone the gene. They're excited about their progress and the long-term potential. The gene and knowledge gleaned from this research can be incorporated into NU's wheat breeding program.

"This work can tell us how to breed and use our genetic resources in the future and the best way to apply the new technologies we've developed," Baenziger said.

Gill also looks beyond locating the gene.

"Once we find that yield gene, we won't have a clue about how it increases yield. Unless we know exactly how it works, it will be difficult to use these genes," he said.

He and Animal Scientist Daniel Pomp head an effort to assure IANR has the research tools to determine how genes function once they're found. This futuristic effort focuses on wheat and pigs. They'll use gene chips –glass plates on which thousands of genes are placed –to study how major genes function and to identify supporting genes.

"We need to start understanding how these genes work for different traits so this information can benefit our growers," Gill said.

A USDA-National Research Initiative competitive grant helps fund the gene search; the Nebraska Wheat Board funds NU's wheat breeding program.

– Vicki Miller

Molecular Geneticist Kulvinder Gill (left) and Wheat Breeder Steve Baenziger examine patterns of DNA from different wheat lines. They head a team of IANR scientists that is zeroing in on a major gene responsible for yield in wheat. This research has narrowed the gene's location to a small segment on the tip of one chromosome.

Research Technician Julie Champoux inserts a piece of wheat DNA into bacteria to copy it as part of efforts to pinpoint the major yield gene.

Research Associate Mohammad Maroof Shah crosses the wheat cultivar Cheyenne and a chromosome substitution line in the greenhouse. The team's functional genomics research would be impossible if not for unique wheat lines developed at NU years ago by Geneticist Rosalind Morris. Each of these unique lines differ by only one chromosome pair, which allows scientists to study that single chromosome's effects.